Category 3: Power Plants, Propulsion, Nuclear, and Engines

How does the Navy utilize the basic steam cycle?

Converts reactor heat to steam, drives turbines for propulsion and electricity.

What happens in the expansion phase of the Main Steam Cycle?

Steam expands in turbines, converting thermal energy to mechanical work.

What is redundancy? List 5 systems/components that are redundant. Include 2 from your community

Redundancy: duplication of critical systems for reliability. Examples: backup generators, emergency pumps, dual control rods, redundant sensors, dual communication lines.

Curtis Stage followed by reaction stage turbine: pressure and velocity change

Curtis stage: velocity increases, pressure drops slightly. Reaction stage: pressure drops, velocity increases gradually.

Why utilize compounding in turbines?

Reduces blade speed, distributes pressure drop, increases efficiency and reduces mechanical stress.

What is a Rateau stage? How does pressure and velocity change?

A stage of impulse turbine with multiple rows of blades. Pressure drops in stationary blades; velocity increases in moving blades.

Purpose of Feedwater Control Valve? How does it work?

Regulates flow of feedwater to boilers/steam generators, maintaining water level and pressure.

What do we use for cooling in the Main Condenser? Why?

Seawater or freshwater cools and condenses steam efficiently, maintaining vacuum for turbine efficiency.

List at least 4 advantages and 4 disadvantages of nuclear power

Advantages: high energy density, low greenhouse emissions, fuel abundance, continuous operation. Disadvantages: radioactive waste, high initial cost, safety risk, long decommissioning.

Difference between nuclear force and electric force

Nuclear force binds protons/neutrons in nucleus; electric force causes repulsion/attraction between charges.

Types of radioactive decay. Block methods

Alpha: helium

How does a diesel engine work? How does this process generate work?

A diesel engine compresses air to high pressure and temperature, then injects fuel, causing combustion. The expanding gases push the piston, producing work on the crankshaft.

What are the similarities and differences between a gasoline and diesel engine?

Similarities: both are internal combustion engines converting chemical energy into mechanical work. Differences: gasoline engines use spark ignition, lower compression ratio; diesel engines use compression ignition, higher efficiency, higher torque.

Explain how a gas turbine engine works

Air is compressed by a compressor, mixed with fuel and burned in a combustion chamber, then hot gases expand through a turbine producing work and thrust.

What are the different uses for compressed air in a GTE?

Compressed air is used for starting the engine, anti

How does a split shaft GTE differ from a single shaft GTE?

Split shaft GTE has separate shafts for turbine and load (allowing independent speed control). Single shaft GTE connects turbine and load on one shaft, limiting operational flexibility.

List the advantages and disadvantages of GTEs

Advantages: high power

What is speed governor? What is an overspeed trip?

Speed governor regulates engine speed automatically. Overspeed trip shuts down the engine to prevent damage if speed exceeds safe limit.

Explain why a Controllable/Reversible Pitch (Variable) Propeller is required. Does a submarine require a CRP Propeller? Why/Why not?

CRP propeller allows control of thrust direction and magnitude without changing shaft rotation. Submarines require CRP for precise maneuvering, reversing, and silent operation.

Describe the 3 plant lineups for GTEs

Simple cycle: compressor → combustor → turbine → exhaust. Combined cycle: adds steam cycle for efficiency. Split

Classify the Main Reduction Gear. Define each classification

Parallel: input and output shafts are parallel. Double helical: intermeshing gears reduce axial thrust. Locked train: two

Why do we need the Main Reduction Gear?

To reduce high turbine rotational speed to a suitable propeller speed while transferring power efficiently.

What does a turning gear do?

Slowly rotates the turbine or shaft to prevent shaft bowing, uneven thermal expansion, and bearing wear when offline.

At All Ahead One Third (A1/3), the propeller is rotating at 25 rpm. At All Ahead Full (AI), the propeller is rotating at 75 rpm. How much more thrust is generated at AI vs A1/3? How much more power is required for the higher bell?

Thrust scales roughly with square of speed: (75/25)² = 9x thrust. Power scales roughly with cube of speed: (75/25)³ = 27x power required.

A pendulum has a bob that weighs 10 kg. The cable for the pendulum is 5 meters long. The pendulum is released from rest, perfectly parallel from the ground. How fast is the pendulum moving when it is at the bottom of its swing?

v = √(2gh) = √(29.815) ≈ 9.9 m/s.

A pendulum has a bob that weighs 10 kg. If the pendulum is pushed from the bottom of its path with a velocity of 10 m/s, what is the maximum height it will travel?

h = v²/(2g) = 100/(29.81) ≈ 5.1 m.

When a pump is in slow speed, it requires 1.5 kW of power. When in fast speed, the pump requires 12 kW. How much greater is fast speed than slow speed?

Fast speed requires 12/1.5 = 8 times more power than slow speed.